| Traditional biological nitrogen removal process always faces carbon insufficiency totreat ammonia-rich wastewater and in turn influence the quality of effluent. CompletelyAutotrophic Nitrogen removal Over Nitrite (CANON) process has several advantagescompared with traditional nitrogen removal process, such as no need of carbon source,aeration saving, sludge reduction and greenhouse gas reduction, which is labeled assustainable nitrogen removal process. However, slow startup and unstable partial nitrificationlimit the development of CANON process and application. In order to have a comprehensiveknowledge about CANON process, present studies focused on the startup of CANON processand its optimization. There are three groups of reactors conducted to do experiments, of whichtwo reactors were started by inoculating CANON sludge while the third one was strated byinoculating the stabilized sludge of former two reactors, and the raw water was wastewaterwithout any organic carbon source.Reactor I is filled with ceramsite and the HRT, temperature and pH were9hours,30±1℃and7.008.08respectively. After60days, reactor I was started successfully in the aeratedenvironment with the total nitrogen removal load of0.79kg·(m3·d)-1and total nitrogenremoval rate of75.57%. Then after a long stable operation, the maximum total nitrogenremoval load was1.10kg·(m3·d)-1and total nitrogen removal rate was86.34%.Reactor Ⅱwas filled with polymeric sponge. At the beginning of startup, inoculating sludgeof reactor Ⅱ was from a CANON reactor and was operated at temperature=30±1℃,pH=7.00~8.08. After62days, the reactor was startup successfully with total nitrogen removalload of0.73kg·(m3·d)-1and total nitrogen removal rate of70.21%.Reactor III filled with Polyester cotton as carrier was started under aerobic condition atHRT=9h, T=26±1℃. After100days, the reactor was started successfully with total nitrogenremoval load of0.75kg·(m3·d)-1and nitrogen removal rate of70.79%.This thesis also analysed the influence of carrier on the performance of CANON. Thereactor with ceramsite was stable and had the optimal total nitrogen removal performancewith DO ranging from1.5to1.75mg·L-1. And when the DO increased to1.75or higher,though the total nitrogen removal rate was still very good, but the partial nitrification wasdisturbed. In reactor with polymeric sponge, the performance of partial nitrification and totalnitrogen removal was keeping well with DO around2.5mg·L-1, which illustrated that thetolerance of reactor with polymeric sponge to DO was better than reactor with ceramsite.After a long time running of the three reactors, the results showed that the performance ofreactor I and reactor II was stable in TN removal while reactor III fluctuated in partialnitrification with low TN removal. All these facts illustrated that ceramsite and polymericsponge were good fillers in CANON reactor and Polyester cotton did not suit.Moreover, this study also experimentally analysed the influence of HRT on theperformance of CANON. The results showed that short HRT was in favour of thestabilization of partial nitrification but undermined the TN removal. In reactors with ceramsite, the optimal HRT and best δNO--N δTN for partial nitrification and TN removal was7h and0.127respectively with TN removal load of1.122kg·(m3·d)-1. And the values for reactorswith polymeric sponge was7h ans0.103with TN removal load of0.863kg·(m3·d)-1.Meanwhile, the deposit on the surface of fillers was studied in this paper. The results showedthat:1) the deposit was Calcium Carbohydrated;2) the production of deposit was due to thesimultaneously chemical, biological reactions;3) the deposit could influence the distributionof substrate to undermine the performance of CANON reactors. |
PDF Full Text Request